Ethylene glycol is produced from ethylene, via the intermediate ethylene oxide Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation:
C2H4O + H2O → HOCH2CH2OH
This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major by products are the ethylene glycol oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol.
Monoethylene glycol (MEG) is an important raw material for industrial applications. A primary use of MEG is in the manufacture of polyester (PET) resins, films and fibers. In addition, MEG is important in the production of antifreezes, coolants, aircraft anti-icer and deicers and solvents.